1. Field of the Invention
The present invention concerns an improved brewing method the benefits of which include substantial time savings in the production of the wort. It also concerns brewing hall installations for implementing this method.
2. Description of the Prior Art
The function of the brewing hall in the brewing process is to produce from water, cereals that are optionally malted and hops a wort which is then fermented.
This stage of the process is discontinuous and is made up of the following five successive operations:
1 Mashing: during this phase the starchy materials in the cereals are converted by enzyme action into elements that can be fermented and proteins are broken down into peptides and amino acids.
2 Filtration: the suspension obtained is then filtered. The insoluble phase, or draff, is washed and optionally pressed to obtain the maximum possible extract from it. The liquid phase, or wort, is boiled.
3 Boiling: the purpose of boiling the wort is to inactivate the enzymes, to sterilize the wort, to coagulate the proteins, to eliminate excess water and unwanted volatile substances and to release the bitter materials present in the hops added at this stage of the process.
4 Clarification of the wort: the boiled wort contains coagulated proteins and hop draff. It is necessary to eliminate this insoluble phase, which is a relatively simple matter using a static or centripetal (whirlpool) settling tank.
5 Cooling: the boiled wort is then cooled to the fermenting temperature. During cooling protein fractions combine with polyphenols to produce a fine precipitate which has no harmful effect on the beer.
To carry out these operations the brewing hall is equipped with a boiler for gelatinizing unmalted cereals such as rice and corn, one or two mashing tanks for malted cereals, a filtration system, one or two brewing kettles, a system for separating the insoluble phase and a cooler.
This design of brewing hall does not make optimum use of the existing plant and makes it difficult to modify the types of operations carried out.
Production is limited in particular by non-optimum use of the brewing kettles. The investment and operating overheads of the installation and regulation and automation of the brewery would benefit from optimization.
The prior art includes various proposals for remedying these drawbacks.
Document GB-A-1 321 009 describes a method of continuous production of wort which involves complete modification of existing brewing halls and has never been adopted for industrial production of beer.
Document DE-A-2 941 698 describes a method intended to reduce the duration of the brewing process by using a cyclone sorting step after the milling of the cereals to separate a starch-rich fraction and a fraction rich in protein but low in starch. Only the starch-rich fraction is used for brewing, the other fraction being put to some other use. This preliminary step takes time, consumes energy and does not make completely cost-effective use of the materials for brewing.
Document U.S. Pat. No. 3,048,489 is directed to reducing the duration of the brewing operations and describes a method including a filtration step after boiling the wort using a single kettle.
The document states that the malt must be very finely ground, to a value of not less than 60 mesh and preferably 100 mesh.
The invention is directed to avoiding the aforementioned drawbacks of prior art installations by offering greater flexibility of operation and use. In particular, it allows the production of several different types of beer (for example, preparation of a wort for top fermentation and of another wort for bottom fermentation) and more generally, through improved use of the plant, reduces costs and facilitates operation.
In the method of the invention, the suspension of cereals that have undergone conventional mashing is boiled in the same kettle, in the absence of hops, after which the wort (suspension) obtained is pumped onto a filter.
The method of the invention uses a thin filter bed (between 20 mm and 100 mm thick, preferably in the order of 40 mm thick), thereby differing from traditional methods which use filter beds in the order of 30 cm thick. The advantage of this is that the filtering time is shorter, but still in accordance with the laws of operation, and the wort obtained has adequate clarity.
After filtration the cake composed of draff is pressed and sparged (washed) and the wort is cooled for subsequent conventional treatment, possibly after passing through a buffer tank.
Because the hops are not added during the mashing-boiling operation, they are introduced in the isomerized form either during fermentation or during storage of the beer.
Hop extract can also be added during bottling or canning.
The cereals employed are not separated into various fractions and are put into suspension in the form of a flour. A non-negligible proportion of this flour (in the order of 30% to 40%) has a particle size such that it cannot pass through the 253 xcexcm screens which are the norm in brewing.
This particle size can be obtained using a hammer grinder with an outlet screen mesh size in the order of 1 mm.
It has been found advantageous to include in the method an intermediate step between boiling and filtration in which the temperature is reduced to a value in the order of 70xc2x0 C. by adding cold water to the wort or by passing the latter through a heat exchanger. The benefit of this operation is that it reduces the concentration of DMS (dimethylsulfide) and of dextrins at the fermentation stage.